Delays were reported throughout the system on trains heading through San Francisco to and from northern stations in the East Bay, and no trains were moving between the Pittsburg-Bay Point and North Concord station.
Trains that were moving were shorter than usual because dozens of cars had to be taken out of service due to unexplained power surges on the Pittsburg-Bay Point line.
“We have shut down that section of track because we can’t afford to damage any more train cars,” BART spokeswoman Alicia Trost told the San Francisco Chronicle newspaper.
“We already have a limited number of cars in our fleet.” she said.
The affected line stretches from San Francisco International Airport through the city and under San Francisco Bay to Oakland and nearly two dozen cities in the East Bay.
BART serves the region with hundreds of cars on four interconnected train lines that carry more than 400,000 passengers daily.
But dozens of cars have had to be taken out of service since the still-unexplained power surges started.
Some 50 train cars stopped working on Wednesday after being overwhelmed by a 2,000-volt power surge north of the North Concord station, the newspaper said.
The power surge was twice the amount of power needed and damaged one of the cars’ vital components, a $1,000 semiconductor device known as a thyristor, although transit officials insisted there was no danger to riders.
“There’s no safety risk or concern for any of the passengers,” Trost said.
BART’s chief mechanical officer, Dave Hardt, told the newspaper that the problem is similar to one that damaged 80 cars in West Oakland in February, but that experts have not been able to figure out why.
“The silver lining is that this is no longer intermittent — all of the cars are failing in the exact same way,” Hardt said.
In theory, that would make it easier to figure out why.
But not this time.
“Recovery of the fleet is going to take months,” Hardt said. “A lot of that is parts, some is elbow grease.”
The BART system needs 570 of its 669 train cars in service every day.
By 8:30 a.m. Friday, BART was reporting 20-minute delays at San Francisco stations for trains headed to the East Bay.
Trains headed south from Daly City, just south of San Francisco, also were experiencing 10-minute delays due to unrelated police activity, the newspaper said.
